Effect of chromogranin A on central autonomic control of blood pressure

We investigated the effect of exogenous chromogranin A (CgA) on central autonomic structures involved in the control of blood pressure. Actions of CgA were assessed on neurons in the rostral ventrolateral medulla, the most important brain area for cardiovascular control and for generation of sympathetic activity. Changes in renal sympathetic nerve activity, arterial pressure, heart rate, and somato-sympathetic reflexes were measured after microinjections of chromogranin A into the rostral ventrolateral medulla of anesthetized rats. The sites of microinjection of chromogranin A were determined from well known sympathetic and cardiovascular responses to microinjection of the inhibitory amino acid glycine. Significant decreases in renal nerve activity and arterial blood pressure began 10 min after microinjection of chromogranin A into the rostral ventrolateral medulla, and the maximum effect was observed at 20 min. Moreover, the bulbar component of somato-sympathetic reflexes was depressed 20 min after microinjections of chromogranin A. Our results indicate that chromogranin A can modify the activity of neurons within rostral ventrolateral medulla involved in regulation of cardiovascular autonomic control.